PHP 7.4 compatibility

[brunobart]

I'm try to use PDFMerge with symfony5.2 (composer require rguedes/pdfmerger)

The folowing error append :

Trying to access array offset on value of type bool
in vendor/rguedes/pdfmerger/Classes/fpdi/fpdi_pdf_parser.php (line 308)
in vendor/rguedes/pdfmerger/Classes/fpdi/fpdi_pdf_parser.php -> _getPageRotation (line 284)
in vendor/rguedes/pdfmerger/Classes/fpdi/fpdi.php -> getPageRotation (line 234)
in vendor/rguedes/pdfmerger/Classes/PDFMerger.php -> importPage (line 88)
PDFMerger->merge('file', 'fusion.pdf')

[jutant-l]

I am also interested by this request